A scale assembly for weighing potentially hazardous materials comprise a containment deck designed to support a container from which materials are dispensed. The containment deck is preferably provided with sufficient storage capacity to capture spillage or leaks from the container and is supported on a low-profile platform supported in turn by load cells which generate signals indicative of the weight of the contents of the container and of any spillage within the containment deck. The containment deck is further equipped with a level detector typically positioned near the bottom of the deck for generating signals indicating the presence of leakage or spillage from the container.